08.18.17 extension cord.jpg

Handy, useful and easy to operate, extension cords make doing tasks at work a lot more convenient. However, if not operated properly, they pose serious dangers such as burns and shock. It may seem silly that a simple cord requires instructions, but there are legitimate dangers involved. 

Extension cords come in two or three-wire types for various uses. The two wire pronged cords are designed for small appliances and generally will not be used on the job. Three-wired cords are beneficial for those who operate power tools. For construction site workers, the National Electric Code requires that specific cords be used. These items are marked with the word “outdoor” or “WA” on the jacket. Cords are also marked with labels regarding usage, size and wattage rating. The gauge of the cord is indicated by a number that corresponds with the item you wish to plug in. Although this may be confusing, the smaller the gauge number on the cord, the larger the power wattage of the appliance. 

Recommendations when using extension cords on the job: 

  • Carefully read the instructions for the power tools you are planning to use to determine the wattage needed from the cord.

  • Look for cords with the UL marking. This means the cord has been tested for safety hazards.
  • Unplug cords when they are not in use, as they still conduct electricity from an outlet.
  • Never use a cord that is cut or damaged. If you touch a piece of wire, you are vulnerable to burning or shocking.
  • Disconnect the cord by the electrical source; do not pull on the cord itself.
  • Use extension cords only on a temporary basis.
  • Insert the plug fully in the outlet so that no part of the prongs are visible.
  • Never use cords with the inappropriate wattage for the tool.
  • Be mindful of where you place cords on the floor. They can be a tripping hazard if you (or someone else) are not careful.
  • If you see extension cords on a regular basis, inspect them habitually for damage to the cord and/or plug.

With the wide use of power tools in our shops and our projects extension cords are necessary. Because they are exposed to hazards common to our work areas (sharp edges, wet conditions, etc.) and are made with flexible soft plastic or rubber covering they are more susceptible to wear and damage than fixed wiring. 

OSHA standards require that extension cords be rated for hard or extra-hard usage. The ratings are derived from the National Electric Code and will be marked approximately every foot along the length of the cord. 

Examples of these codes are: 

• S, ST, SO and STO for hard service,

•  SJ, SJO, SJT and SJTO for junior hard service

For more on extension cord safety and care, please see this edition of Wachs Weekly!